The carbon pathway for and regulation of gluconeogenesis will be studied under experimental conditions which might be applicable to human metabolism. Experiments will be carried out with a number of animals, including tetrahymena pyriformis, which are representative of a varied subcellular distribution and isozyme content of PEP carboxykinase. The regulation of gluconeogenesis will be correlated with the distribution of the PEP enzyme and the effect of long chain acyl CoA esters on adenine nucleotide translocation across the liver inner mitochondrial membrane. Because of the potential importance of the translocation of adenine nucleotides (ATP,ADP) to cell metabolism in general, and the fact that long chain acyl CoA's are the only known natural effectors of this system, a careful investigation of the interrelationship acyl CoA esters and translocase activity in other tissues, particularly the heart, will be carried out. The regulation of gluconeogenesis at the level of protein synthesis will be studied in tetrahymena. Experiments will be continued to determine whether the increase in gluconeogenesis following inhibition of protein synthesis is controlled at the site of amino acylation of t- RNA and/or peptide chain initiation on the ribosome. The possibility that inhibition of protein synthesis at a specific site initiates a chain of events leading to the intracellular accumulation of amino acids which are transaminated and converted to carbohydrate will be considered.